When the automobile was first invented, no one gave much thought to the trash it would produce. At that time, when the tires wore out, they were thrown out. Most ended up in land fills or were burned, but neither disposal method has been acceptable. Over time, tires tend to "float" to the surface of a landfill. Also, burning is popular with no one, due to the pollution and smell. Some tires are retreaded and reused, but the majority must still be disposed in some fashion.
The number of discarded tires is increasing, and the problems with traditional disposal methods are becoming more acute. For example, many landfills now either refuse to take tires or are prevented from doing so by legislation. The burning of tires in the outside air is both a pollutant and a nuisance to those nearby and has also been made illegal in many locations. Therefore, there is a need for a method and device for disposing of tires without burning or disposing in a landfill.
Luckily, there is also a market for granularized rubber of the type used in tires. For example, granularized rubber can be used as a filler in construction work, or as a fuel in some plants. Therefore, if the tires can be reduced to a granularized form, much of the old tire disposal problem can be alleviated.
The disposal need has been recognized for many years, and many have tried to invent processes and devices for disposing of old tires. Those efforts can be grouped into three basic groupings: shredders, temperature treatments, and chemical treatments. Examples are seen in the following U.S. Pat. Nos., all of which are incorporated herein by reference: 5,048,764 Flament; 4,927,088 Brewer; 4,854,508 Dicky; 4,776,249 Barclay; 4,684,070 Dicky; 4,635,862 West, et al.; 4,093,129 Polansky; 4,726,530 Miller, et al.; 4,714,201 Rouse, et al.; 4,863,106 Perkel; 4,813,614 Moore, et al.; 4,240,587 Letsch; 3,992,899 Spahn; 4,273,000 Schmid; 4,200,400 Laubach, et al.; 2,702,217 Treshow; 2,135,440 Longenecker, et al.; 1,911,514 Kernan; 1,766,582 Ball; 1,298,743 Lichtenberg; 1,087,967 Moussette; 4,052,344 Crane, et al; 3,880,807 Wakefield, et al; 3,809,680 Wakefield; 3,896,059 Wakefield, et al; 3,946,680 Laman; 3,890,141 Crane, et al; 3,582,279 Beckman, et al; 3,772,242 Liska, et al; 4,221,608 Beckman; 3,966,487 Crane, et al; 3,823,224 Laman, et al; 3,907,583 Crane; and 3,823,221 Wakefield, et al.
One major problem with shredding, at least as practiced to date, is that the belts of steel belted tires wrap around the shredding blades and other apparatus, thereby tearing up the shredder. Chemical processes have waste problems of their own, and they are not useful to reduce the tire to a granular form for use in construction. Freezing and breaking the tire avoids the chemical effluent problem, and avoids having a shredder destroyed by the steel belts, but the process requires a large amount of energy and requires further processing to remove the belts. Then, the broken tire bits must be further reduced to a size useful in other markets, such as construction.
Recently, it was suggested that a way to avoid the above problems was to grind the tires, rather than shred them. The theory was that if all of the tire, including the steel belts, could be ground to a granular size, then there would not be a problem with the steel belts wrapping around rotating blades and bearings, thereby tearing up the shredder, itself. To try this concept, a series of sharp grinding bits were applied to steel plates, and the plates were bolted to the outer surface of a rotatable drum. A straight plate was then mounted tangentially to the drum's surface to act as a funnel, and tire scraps were dropped between the drum and the straight plate. The bits were knocked from the plates and the tire scraps were not ground. The experiment Was a failure.
Therefore, at the time of the present invention, there was a need for a device and method of commutating tires (herein, "tires" includes whole tires and tire scraps), some of which include steel belts, that would not require a freezing and breaking step. There was also a need for a method and device which would not have to use shredding blades that allowed the steel to wrap up in the rotating apparatus.